Since virtually the inception of molecular biology, the detection of nucleic acids (both DNA and RNA) has turned on the incorporation of various labels into these molecules. At first, radioactive labels such as 32P were widely using in southerns, northerns and sequencing. Later, a great number of non-radioactive labels were developed, having groups which either fluoresced themselves or fluoresced upon interactions with a second molecule (e.g. biotin). It is an object of the present invention to develop methods and instruments which are capable of detecting nucleic acids without introduction of any type of exogenous label.